Couch
Part of speech: noun
Definition: An item of furniture for the comfortable seating of more than one person. Bed, resting-place.
Part of speech: verb
Definition: To lie down; to recline (upon a couch). To phrase in a particular style, to use specific wording.
Example sentence: We are human beings, you need to mentally switch off now and again to refresh your body and mind. But I never just lie on the couch in my downtime, I still keep my body in good shape.
Sofa
Part of speech: noun
Definition: An upholstered seat, typically having sides and back, long enough to accommodate two or more people.
Example sentence: So many people condemn me for risk taking, but I find it sort of hypocritical because everybody takes risks. Even the absence of activity could be viewed as a risk. If you sit on the sofa for your entire life, you're running a higher risk of getting heart disease and cancer.